This invention relates to a tractor drive for continuous paper having perforated edges for use in typewriters or similar office machines. The tractor drive is of the type which has tractor members which are rotated by a drive shaft and which are shiftable axially, that is, parallel to the width of the continuous paper and can be immobilized in a desired position to thus accurately align the respective toothed transporting (tractor) belts, each driven by a toothed gear, with the marginal holes provided in the continuous paper.
In conventional continuous paper feeders or continuous paper transporting devices for information processing machines it is known to drive an endless transporting belt by a toothed gear meshing with teeth on the inwardly-oriented face of the belt. The outwardly-oriented belt face has driving pins which engage in the marginal holes of the continuous paper for a continuous feed. A major difficulty encountered in these transporting devices is aligning the transporting belts and the pins accurately to mate with the marginal holes in the continuous paper.
To overcome this difficulty, according to U.S. Pat. No. 4,735,352, the two tractors are axially displaceable on a drive shaft and a guide bar and they can be immobilized in the desired axial position by tightening them to the guide bar by means of a clamping device. This tractor device which includes a drive shaft and an additional guide bar is too complex and expensive for low-cost office machines.